Rotating type carrier with shiftable hammer carrier

ABSTRACT

PRINTING ARRANGEMENT FOR HIGH-SPPED PRINTERS WITH ROTATING TYPE CARRIER AND SEVERAL PRINT HAMMERS, CONSISTING OF A UNIT WHICH IS UNIFORMLY MOVED ALONG THE PRINTING LINE DURING PRINTING. A MINIMUM RELATIVE SPEED BETWEEN   THE RECORD CARRIER AND THE FIRED TYPES IS OBTAINED BY MEANS OF A PERIODICALLY SHIFTED HAMMER CARRIER.

NOV. 30, 1971 BUEHRMANN ETAL 3,623,427

ROTATING TYPE CARRIER WITH SHIFTABLE HAMMER CARRIER Filed April 8, 1969 INVENTORS GEROLD BUEHRMANN GUENTER H. SCHACHT ATTORNEY United States Patent U.S. Cl. 101-93 2 Claims ABSTRACT OF THE DISCLOSURE Printing arrangement for high-speed printers with rotating type carrier and several print hammers, consisting of a unit which is uniformly moved along the printing line during printing. A minimum relative speed between the record carrier and the fired types is obtained by means of a periodically shifted hammer carrier.

SUMMARY OF THE INVENTION The invention relates to a storage-controlled printing arrangement for high-speed printers, in particular for high-speed printers used as output units of data processors, with uniformly rotating type carrier comprising all characters to 'be printed at least once and several parallel print hammers.

Printing arrangements, in particular those used as output units of data processors, have become known in great number. US. Pat. 2,692,551 refers to a print mechanism with rotating type carrier in which the type sequence is arranged on a type wheel rotating at a constant angular speed. In their inoperative position the print hammers form a circular arc disposed coaxially in relation to the type wheel. The printing paper, bent coaxially in relation to the type wheel, passes in between the print hammers and the type wheel. The quality of the paper has to meet special requirements, since the line feed accelerations occurring in up-to-date printers exert high stresses on the paper in the bent state. In addition to the difiiculty of the design of the paper guides necessitating a great overall height of the printer in the case of great line lengths, there is the disadvantage of substantial means being required for the control of the print hammers, since each printing position of the line has to be provided with a hammer of its own.

DAS 1,248,341 (German published patent application No. 1,248,341) relates to a print mechanism for printing machinery with rotating type carrier in which a type roll rotates in front of a record carrier, identical types being preferably arranged in one line along the geneatrix. Superposition of an oscillating movement upon the relative movement between the type carrier and the record carrier to be printed leads to the types being actuated at the relative speed between the type carrier and the record carrier. As soon as the required types of the type carrier have been accurately aligned in relation to the printing positions on the record carrier, the print hammers are fired onto the respective types. As in this case, too, a separate print hammer is required for each printing position of the line, the control means to be used are substantial. Moreover, the type carrier has a large diameter and a correspondingly high moment of inertia, since for each printing position within the line each character to be printed has to be available at least once on the roll surface.

US. Pat. 2,911,085 describes a printer in which a wire head is uniformly guided along the line to be printed, an oscillating pivotal movement being superposed upon this 3,623,427 Patented Nov. 30, 1971 uniform movement to reduce the relative speed between the printing head and the record carrier during printing. To this end the printing head can be pivoted about an axis disposed vertically in relation to the direction of the line. This arrangement has the disadvantage that the drive used for the pivotal movement consists of two Bowden wires so that even after a short period of operation the quality of the image is impaired, since an accurate adjustment of the printing head is no longer guaranteed. Further difficulties are caused by the driving elements of the wire pins producing the image being firmly attached to the machine, while the printing head has to be moved along the printing line, which may comprise, for example, some printing positions.

British patent specification 994,159 describes a printing arrangement in which the paper to be printed is arranged between a uniformly rotating type carrier, which may take the form of a type roll or a type chain, and a print hammer movable in the direction of the line. The print hammer and the associated drive move stepwise along the line from printing position to printing position. In this arrangement the time required for printing is primarily governed by the speed of the type chain or the type roll. The maximum speed of rotation of the type carrier is limited by the requirements of a clear image. Although the number of print hammers required is reduced in this arrangement, the length of the type roll or the type chain is the same as in printers using a separate hammer for each printing position.

It is the object of the invention to provide a printing arrangement ensuring a high printing speed and a clear image, using few movable components.

To this end the invention is characterized in that a printer unit is provided which during printing is uniformly moved along the printing line and which consists of a rotating type chain, several parallely operating print hammers and the guide and actuating means required. This arrangement has the advantage that lines of any length can be printed. The small number of movable components used ensures that the susceptability to breakdowns is greatly reduced. The whole unit is readily exchangeable so that repairs can be carried out within a very short time. The drive power required is low, since the small mass of the printing unit is moved uniformly in the direction of the line.

A particularly favorable embodiment of the invention is characterized in that in order to obtain a minimum relative speed between the record carrier and the fired type during printing the print hammers are supported in a hammer carrier which is periodically shifted by means of a uniformly rotating eccentric or cam so that the trans fer speed of the unit along the printing line can be chosen very high without impairing the quality of the image.

Details of the invention will be apparent from the claims and the following more particular description of the invention as illustrated in the drawing.

The printer unit 1 shown in the figure is slidably mounted on and guided in the direction of the printing by a fixed line guide rod 7. For the sake of ready discernibility, the chain mounting 11, which with the type chain 10 and types 9 forms part of the unit 1, is shown in an exploded view. In the operational position, the chain mounting 11 with the type chain 10 is attached to the drive shafts 6 by interconnection of gear 6a with corresponding toothed opening 15a in drive wheel 15, driving the chain 10, being secured to housing 13 by means such as screw 14. During printing the printer unit 1 carrying the type chain 10 and print hammers 3 moves on the guide rod 7 at a constant speed along the printing line, for example, in accordance with the European way of writing from left to right. The printer unit 1, the drive of which was omitted in order not to unduly complicate the drawing, may be driven by a tape, rope or chain drive system. Equally suitable are one or several spindles which are arranged parallel in relation to the direction of the line and which are driven by means of a motor attached to the machine frame not shown. The hammer carrier 2 is mounted on the housing 13 of the printer unit 1 by means of an elastic pivot comprising two leaf springs 12. The arrangement shown is for a front printer, and print hammers 3 are so supported in the hammer carrier 2 being for example pivotally mounted on a threaded rod 2!) extending through the carrier 2 and which secures the springs 12 thereto that they can perform a pivotal movement in the direction of the types 9 to be fired for impacting the type 9 against a record on which a printing operation is to be performed. The print hammers 3 are biased in the direction of the housing 13 by spring tension. The actuating or drive elements 5 which may be the armatures of drive magnets (not completely shown) and the print hammers 3 are positively connected by means of push rods 4 in a manner similar to that disclosed in US. Pat. No. 3,433,153, which issued Mar. 18, 1969, to R. H. Harrington et al. The hammer carrier 2 can be laterally moved in opposite directions in relation to the housing 13 lengthwise of the guide rod 7. A shaft carrying on its end an eccentric 8, or other cam means, is arranged almost in the centre of the front plate of the housing 16, On the front plate of the housing 13 are moreover arranged two drive shafts 6, at least one of which has a gear 6a on its end to drive the type chain 10 with the types 9 guided and supported on the chain mounting 11 by leaf spring portions 9a. In addition to the print hammer drive elements 5, the housing 13 accommodates a motor 16 which causes both the drive shafts 6 for the type chains and the eccentric 8 to be uniformly rotated. The eccentric 8, through the arms 2a, transmits its movement to the hammer carrier 2 so that the latter performs an oscillating movement in the direction of the printing line. As this oscillation and the continuous movement of the printer unit 1 along the printing line are performed at times in the same direction, there results a superposition of the two movements for the hammer carrier 2 and the print hammers 3 which are supported in the latter. By suitably selecting the frequency and the amplitude of the oscillation in relation to the continuous speed of the printer 1, taking into account the spacing between two characters to be printed, a temporary standstill or a minimtun speed of the print hammers 3 in relation to the record on which printing is to be effected can be obtained.

At the beginning of the time interval of the minimum relative speed between the print hammers 3 and the record, a type 9 has to be aligned in relation to each printing hammer 3 so that during this interval printing can be performed. This can be obtained in an advantgeous manner by the eccentric 8 and the drive shafts 6 for the type chain 10 being geared to each other, using a common drive motor 16-. If at the beginning of such a time interval a desired one of the types 9 is in a print position of the record onto which it is to be fired, it is activated by the associated print hammer 3. As the type chain 10 during this time interval continues moving at a uniformly high speed, blurring of the character printed onto the record carrier would be inevitable. For this reason the types 9 are elastically linked with the type chain 10 which may comprise for example a rubber belt or the like similar to that disclosed in the Hense Pat. No.

4 2,936,704, issued May 17, 1960 so that a short standstill of the types 9 in relation to the record carrier is ensured during firing. This elastic connection in the direction of the line is preferably suitably clamped in order to prevent subsequent oscillations of the types 9.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from. the spirit and scope of the invention.

What is claimed is:

1. In a high speed printer unit disposed on one side of a record for printing thereon,

a printer unit housing mounted on a fixed guide for movement along a print line of said record,

a type chain mounted on said housing for rotational movement relative thereto and having a plurality of type carrying fingers with a portion of said type chain being movable along said print line and said fingers being disposd to be impacted against said record for printing thereon,

a hammer carrier having a plurality of print hammers mounted on said housing on the opposite side of said type chain from said record and movable along said print line with said housing for impacting said type carrying fingers against said record,

support means comprising a pair of leaf springs connecting said hammer carrier to said housing to provide limited resilient movement of said hammer carrier back and forth relative to said housing in a direction along said print line,

operating means carried by said housing periodically moving said hammer carrier back and forth on said housing along the print line and,

common drive means for moving said type chain and said hammer carrier operating means in timed relation.

2. The invention as defined in claim 1 characterized by said operating means comprising a cam driven by a motor mounted on the printer unit housing, and follower arms depending from said hammer carrier, said motor being also operatively connected to drive said type chain so that the type chain and hammer carrier move in timed relation with each other.

References Cited UNITED STATES PATENTS WILLIAM B. PENN,

US. Cl. X.R.

Primary Examiner 

